The amino sugar methyl L-daunosaminide, i.e. the compound of the formula ##STR1## is a known coupling agent with the antibiotic daunomycinone or adriamycinone to produce the natural antibiotics daunomycin and adriamycin respectively. See Arcamone et al. J. of Med. Chem., 1975, Vol. 18, No. 7, pages 703 and Arcamone et al., Cancer Chemotherapy Rep., 6, 123 (1975). In accordance with the aforementioned Arcamone et al. articles, methyl L-acosaminide which has the formula: ##STR2## is converted to C4'epi-daunomycin and C4'epi-adriamycin, known antitumor agents, by forming a derivative of the compound of formula I-B, i.e. a compound of the formula ##STR3## via the procedure described by Fuchs, J. Antibiotics, 32, 223 (1979).